diff --git a/app/internal/http/server.go b/app/internal/http/server.go
index e5761ce5f1..760e9e1d45 100644
--- a/app/internal/http/server.go
+++ b/app/internal/http/server.go
@@ -278,6 +278,9 @@ func sendSimpleResponse(conn net.Conn, req *http.Request, statusCode int) error
 		ProtoMinor: req.ProtoMinor,
 		Header:     http.Header{},
 	}
+	// Remove the "Content-Length: 0" header, some clients (e.g. ffmpeg) may not like it.
+	// NOTE: This will also cause go/http to add a "Connection: close" header, but seems to be fine.
+	resp.ContentLength = -1
 	return resp.Write(conn)
 }